Sir Robert Alexander Watson-Watt,[a] KCB, FRS, FRAeS (13 April 1892
– 5 December 1973) was a Scottish pioneer of radio direction finding
and radar technology.
Watt began his career in radio physics with a job at the Met Office,
where he began looking for ways to accurately track thunderstorms
using the radio signals given off by lightning. This led to the 1920s
development of a system later known as huff-duff. Although well
publicized at the time, the system's enormous military potential was
not developed until the late 1930s. Huff-duff allowed operators to
determine the location of an enemy radio in seconds and it became a
major part of the network of systems that helped defeat the U-boat
threat. It is estimated that huff-duff was used in about a quarter of
all attacks on U-boats.
In 1935 Watt was asked to comment on reports of a German death ray
based on radio. Watt and his assistant
Arnold Frederic Wilkins
Arnold Frederic Wilkins quickly
determined it was not possible, but Wilkins suggested using radio
signals to locate aircraft at long distances. This led to a February
1935 demonstration where signals from a
BBC short-wave transmitter
were bounced off a
Handley Page Heyford
Handley Page Heyford aircraft. Watt led the
development of a practical version of this device, which entered
service in 1938 under the code name Chain Home. This system provided
the vital advance information that helped the
Royal Air Force
Royal Air Force win the
Battle of Britain.
After the success of his invention, Watson-Watt was sent to the US in
1941 to advise on air defence after Japan’s attack on Pearl Harbor.
He returned and continued to lead radar development for the War
Ministry and Ministry of Supply. He was elected a Fellow of the Royal
Society in 1941, was given a knighthood in 1942 and was awarded the US
Medal for Merit
Medal for Merit in 1946.
1 Early years
2 Early experiments
3.1 The air defence problem
3.2 Aircraft detection and location
4 Civil Service trade union activities
5 Contribution to Second World War
8 Family life
9 See also
13 External links
Born in Brechin, Angus, Scotland, on 13 April 1892 Watson-Watt (the
hyphenated name is used herein for consistency, although he did not
adopt it until 1942) was a descendant of James Watt, the famous
engineer and inventor of the practical steam engine. After attending
Damacre Primary School and
Brechin High School, he was accepted to
University College, Dundee (then part of the University of St Andrews
but became the
University of Dundee
University of Dundee in 1967). Watson-Watt had a
successful time as a student, winning the Carnelley Prize for
Chemistry and a class medal for Ordinary Natural Philosophy in
He graduated with a BSc in engineering in 1912, and was offered an
assistantship by Professor William Peddie, the holder of the Chair
of Physics at University College, Dundee from 1907 to 1942. It was
Peddie who encouraged Watson-Watt to study radio, or "wireless
telegraphy" as it was then known, and who took him through what was
effectively a postgraduate class of one on the physics of radio
frequency oscillators and wave propagation. At the start of the Great
War Watson-Watt was working as an assistant in the College's
In 1916 Watson-Watt wanted a job with the War Office, but nothing
obvious was available in communications. Instead he joined the
Meteorological Office, which was interested in his ideas on the use of
radio for the detection of thunderstorms.
Lightning gives off a radio
signal as it ionizes the air, and his goal was to detect this signal
to warn pilots of approaching thunderstorms. The signal occurs across
a wide range of frequencies, and could be easily detected and
amplified by naval longwave sets – in fact, lightning was a major
problem for communications at these common wavelengths.
His early experiments were successful in detecting the signal and he
quickly proved to be able to do so at ranges up to 2,500 km.
Location was determined by rotating a loop antenna to maximise (or
minimise) the signal, thus "pointing" to the storm. The strikes were
so fleeting that it was very difficult to turn the antenna in time to
positively locate one. Instead, the operator would listen to many
strikes and develop a rough average location.
At first, he worked at the Wireless Station of Air Ministry
Meteorological Office in Aldershot, Hampshire. In 1924 when the War
Department gave notice that they wished to re-occupy their Aldershot
site, he moved to
Ditton Park near Slough, Berkshire. The National
Physical Laboratory (NPL) was already using this site and had two main
devices that would prove pivotal to his work.
The first was an Adcock antenna, an arrangement of four masts that
allowed the direction of a signal to be detected through phase
differences. Using pairs of these antennas positioned at right angles,
one could make a simultaneous measurement of the lightning's direction
on two axes. Displaying the fleeting signals was a problem. This was
solved by the second device, the WE-224 oscilloscope, recently
acquired from Bell Labs. By feeding the signals from the two antennas
into the X and Y channels of the oscilloscope, a single strike caused
the appearance of a line on the display, indicating the direction of
the strike. The scope's relatively "slow" phosphor allowed the signal
to be read long after the strike had occurred. Watt's new system
was being used in 1926 and was the topic of an extensive paper by Watt
The Met and NPL radio teams were amalgamated in 1927 to form the Radio
Research Station with Watt as director. Continuing research
throughout, the teams had become interested in the causes of "static"
radio signals, and found that much could be explained by distant
signals located over the horizon being reflected off the upper
atmosphere. This was the first direct indication of the reality of the
Heaviside layer, proposed earlier but at this time largely dismissed
by engineers. To determine the altitude of the layer, Watt, Appleton
and others developed the 'squegger' to develop a 'time base' display,
which would cause the oscilloscope's dot to move smoothly across the
display at very high speed. By timing the squegger so that the dot
arrived at the far end of the display at the same time as expected
signals reflected off the Heaviside layer, the altitude of the layer
could be determined. This time base circuit was key to the development
After a further reorganization in 1933, Watt became Superintendent of
Radio Department of NPL in Teddington.
The air defence problem
During the First World War, the Germans had used Zeppelins as
long-range bombers over London and other cities and defences had
struggled to counter the threat. Since that time aircraft capabilities
had improved considerably and the prospect of widespread aerial
bombardment of civilian areas was causing the government anxiety.
Heavy bombers were now able to approach at altitudes that
anti-aircraft guns of the day were unable to reach. With enemy
airfields across the English Channel potentially only 20 minutes’
flying-time away, bombers would have dropped their bombs and be
returning to base before any intercepting fighters could get to
altitude. The only answer seemed to be to have standing patrols of
fighters in the air at all times but, with the limited cruising time
of a fighter, this would require a huge air force. An alternative
solution was urgently needed and in 1934, the
Air Ministry set up a
committee, the CSSAD (Committee for the Scientific Survey of Air
Defence), chaired by Sir
Henry Tizard to find ways to improve air
defence in the UK.
Nazi Germany was rumoured to have a "death ray" using radio waves that
was capable of destroying towns, cities and people. In January 1935,
Harry Wimperis, Director of Scientific Research at the Air Ministry,
asked Watson-Watt about the possibility of building their version of a
death-ray, specifically to be used against aircraft. Watson-Watt
quickly returned a calculation carried out by his young colleague,
Arnold Wilkins, showing that the device was impossible to construct,
and fears of a Nazi version soon vanished. He also mentioned in the
same report a suggestion that was originally made to him by Wilkins,
who had recently heard of aircraft disturbing shortwave
communications, that radio waves may be capable of detecting aircraft:
"Meanwhile attention is being turned to the still difficult, but less
unpromising, problem of radio detection and numerical considerations
on the method of detection by reflected radio waves will be submitted
when required." Wilkins's idea, checked by Watt, was promptly
presented by Tizard to the CSSAD on 28 January.
Aircraft detection and location
Memorial at the
Daventry site of the first successful RADAR
experiments. 52°11′46″N 1°03′00″W / 52.195982°N
1.050121°W / 52.195982; -1.050121
Closeup of memorial plaque
The first workable radar unit constructed by Robert Watson Watt and
On 12 February 1935, Watson-Watt sent the secret memo of the proposed
system to the Air Ministry, Detection and location of aircraft by
radio methods. Although not as exciting as a death-ray, the concept
clearly had potential but the Air Ministry, before giving funding,
asked for a demonstration proving that radio waves could be reflected
by an aircraft. This was ready by 26 February and consisted of two
receiving antennas located about 6 miles (9.7 km) away from one
of the BBC's shortwave broadcast stations at Daventry. The two
antennas were phased such that signals travelling directly from the
station cancelled themselves out, but signals arriving from other
angles were admitted, thereby deflecting the trace on a CRT indicator
(passive radar). Such was the secrecy of this test that only three
people witnessed it: Watson-Watt, his colleague Arnold Wilkins, and a
single member of the committee, A. P. Rowe. The demonstration was a
success; on several occasions a clear signal was seen from a Handley
Page Heyford bomber being flown around the site. The Prime Minister,
Stanley Baldwin, was kept quietly informed of radar's progress. On 2
April 1935, Watson-Watt received a patent on a radio device for
detecting and locating an aircraft.
In mid-May 1935, Wilkins left the
Radio Research Station with a small
party, including Edward George Bowen, to start further research at
Orford Ness, an isolated peninsula on the Suffolk coast of the North
Sea. By June they were detecting aircraft at a distance of 16 miles
(26 km), which was enough for scientists and engineers to stop
all work on competing sound-based detection systems. By the end of the
year the range was up to 60 miles (97 km), at which point plans
were made in December to set up five stations covering the approaches
One of these stations was to be located on the coast near Orford Ness,
Bawdsey Manor was selected to become the main centre for all radar
research. In an effort to put a radar defence in place as quickly as
possible, Watson-Watt and his team created devices using existing
available components, rather than creating new components for the
project, and the team did not take additional time to refine and
improve the devices. So long as the prototype radars were in workable
condition they were put into production. They soon conducted "full
scale" tests of a fixed radar radio tower system that would soon be
known as Chain Home, an early detection system that attempted to
detect an incoming bomber by radio signals. The tests were a
complete failure, with the fighter only seeing the bomber after it had
passed its target. The problem was not the radar, but the flow of
information from trackers from the
Observer Corps to the fighters,
which took many steps and was very slow.
Henry Tizard with Patrick
Hugh Dowding immediately set to work on this problem,
designing a 'command and control air defence reporting system' with
several layers of reporting that were eventually sent to a single
large room for mapping. Observers watching the maps would then tell
the fighter groups what to do via direct communications.
Radar coverage along the UK coast, 1939–1940
By 1937 the first three stations were ready, and the associated system
was put to the test. The results were encouraging, and an immediate
order by the government to commission an additional 17 stations was
given, resulting in a chain of fixed radar towers along the east and
south coast of England. By the start of the Second World War,
19 were ready to play a key part in the Battle of Britain, and by the
end of the war over 50 had been built. The Germans were aware of the
Chain Home but were not sure of its purpose. They
tested their theories with a flight of the
Zeppelin LZ 130, but
concluded the stations were a new long-range naval communications
As early as 1936, it was realized that the
Luftwaffe would turn to
night bombing if the day campaign did not go well, and Watson-Watt had
put another of the staff from the
Radio Research Station, Edward
Bowen, in charge of developing a radar that could be carried by a
fighter. Night time visual detection of a bomber was good to about
300 m, and the existing
Chain Home systems simply did not have
the accuracy needed to get the fighters that close. Bowen decided that
an airborne radar should not exceed 90 kg (200 lb) in weight or
8 ft³ (230 L) in volume, and should require no more than 500
watts of power. To reduce the drag of the antennas the operating
wavelength could not be much greater than one m, difficult for the
day's electronics. "AI" - Airborne Interception, was perfected by
1940, and was instrumental in eventually ending the Blitz of 1941.
Watson-Watt justified his choice of a non-optimal frequency for his
radar, with his often-quoted “cult of the imperfect,” which he
stated as “Give them the third-best to go on with; the second-best
comes too late, [and] the best never comes.”
Civil Service trade union activities
Between 1934 and 1936, Watson-Watt was president of the Institution of
Professional Civil Servants, now a part of Prospect, the "union for
professionals". The union speculates that at this time he was involved
in campaigning for an improvement in pay for
Air Ministry staff.
Contribution to Second World War
Sir Robert Alexander Watson-Watt, ca. 1944
In his English History 1914–1945, historian
A. J. P. Taylor
A. J. P. Taylor paid the
highest of praise to Watson-Watt, Sir
Henry Tizard and their
associates who developed and put in place radar, crediting them with
being fundamental to victory in the Second World War.
In July 1938, Watson-Watt left
Bawdsey Manor and took up the post of
Director of Communications Development (DCD-RAE). In 1939, Sir George
Lee took over the job of DCD, and Watson-Watt became Scientific
Advisor on Telecommunications (SAT) to the Ministry of Aircraft
Production, travelling to the US in 1941 to advise them on the severe
inadequacies of their air defence, illustrated by the Pearl Harbor
attack. He was knighted by
George VI in 1942 and received the US Medal
for Merit in 1946.
Sir Robert descends from a plinth in Trafalgar Square, London in 1961
after speaking at a rally protesting at the spread of nuclear weapons
Ten years after his knighthood, Watson-Watt was awarded £50,000 by
the UK government for his contributions in the development of radar.
He established a practice as a consulting engineer. In the 1950s, he
Canada and later he lived in the US, where he published Three
Steps to Victory in 1958. Around 1958, he appeared as a mystery
challenger on the American television programme To Tell The Truth.
Watson-Watt reportedly was pulled over for speeding in
Canada by a
radar gun-toting policeman. His remark was, "Had I known what you were
going to do with it I would never have invented it!". He wrote an
ironic poem ("Rough Justice") afterwards:
Pity Sir Robert Watson-Watt,
strange target of this radar plot
And thus, with others I can mention,
the victim of his own invention.
His magical all-seeing eye
enabled cloud-bound planes to fly
but now by some ironic twist
it spots the speeding motorist
and bites, no doubt with legal wit,
the hand that once created it.
In 1945 Watson-Watt was invited to deliver the Royal Institution
Christmas Lecture on Wireless.
In 1949 a Watson-Watt Chair of Electrical Engineering was established
at University College, Dundee.
In 2013 he was one of four inductees to the Scottish Engineering Hall
Memorial to Watson-Watt at
Brechin in Angus, Scotland
Memorial to the Birth of Radar, at Stowe Nine Churches, naming
Watson-Watt and Arnold Wilkins
On 3 September 2014 a statue of Sir
Robert Watson-Watt was unveiled in
Brechin by HRH the Princess Royal.
On 4 September Watson-Watt featured in the
BBC Two drama Castles in
the Sky, with
Eddie Izzard in the role.
A collection of some of the correspondence and papers of Watson-Watt
is held by the National Library of Scotland. A collection of
papers relating to Watson-Watt is also held by Archive Services at the
University of Dundee.
A briefing facility at
RAF Boulmer has been named the Watson-Watt
auditorium in his honour.
Watson-Watt was married on 20 July 1916 in Hammersmith, London to
Margaret Robertson (d.1988), the daughter of a draughtsman; they later
divorced and he remarried in 1952 in Canada. His second wife was
Jean Wilkinson, who died in 1964. He returned to Scotland in the
In 1966, at the age of 74, he proposed to Dame Katherine Trefusis
Forbes, who was 67 years old at the time and had also played a
significant role in the
Battle of Britain
Battle of Britain as the founding Air
Commander of the Women's Auxiliary Air Force, which supplied the
radar-room operatives. They lived together in London in the winter,
and at "The Observatory" – Trefusis Forbes' summer home in
Pitlochry, Perthshire, during the warmer months. They remained
together until her death in 1971. Watson-Watt died in 1973, aged 81,
in Inverness. Both are buried in the churchyard of the Episcopal
Church of the Holy Trinity at Pitlochry.
History of radar
^ Originally just "Watt", he added the "Watson-" in 1942.
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^ a b c "British Patent for
Radar System for Air Defense Granted to
Robert Watson-Watt". American Physical Society. 17 February 2017.
Archived from the original on 2 December 2016.
^ Watson-Watt, Sir Robert; The Pulse of Radar, Dial Press, 1959
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^ Shafe, Michael (1982). University Education in Dundee 1881–1981: A
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^ a b c Brown 1999, p. 45.
^ Brown 1999, p. 46.
^ R. A. Watt and J. F. Herd, "An instantaneous direct-reading
radiogoniometer" Archived 2 February 2014 at the Wayback Machine.,
Journal of the Institution of Electrical Engineers, Volume 64
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^ O. S. Puckle, "Time Bases, Their Design and Development", Chapman
& Hall, 1943
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Brown, Louis (1999). Technical and Military Imperatives: A Radar
History of World War 2. CRC Press. ISBN 978-1-4200-5066-0.
Lem, Elizabeth, The
Ditton Park Archive
Celinscak, Mark. "Robert Watson-Watt" in Philosophers of War: The
Evolution of History's Greatest Military Thinkers. Santa Barbara:
ABC-CLIO. p. 489.
Robert Watson-Watt bio
Royal Air Force
Royal Air Force Air Defence
Radar Museum at RRH Neatishead,
The Watson-Watt Society of Brechin, Angus, Scotland
Radar Myths of
World War II
World War II A comparison of
contemporary British and German radar inventions and their use
Radar Development In England
Sir Robert Alexander Watson-Watt's biography
Robert Watson-Watt Society
Air Defence of Great Britain
Air Defence of Great Britain during the Second World War
Royal Air Force
Royal Canadian Air Force
Big Wing formation
R. V. Jones
RAF Fighter Command
RAF Balloon Command
RAF Coastal Command
RAF Bomber Command
No. 9 Group RAF
No. 10 Group RAF
No. 11 Group RAF
No. 12 Group RAF
No. 13 Group RAF
No. 14 Group RAF
1 AA Corps
2 AA Corps
3 AA Corps
1 AA Division
2 AA Division
3 AA Division
4 AA Division
5 AA Division
6 AA Division
7 AA Division
8 AA Division
9 AA Division
10 AA Division
11 AA Division
12 AA Division
Battle of Britain
Battle of Britain airfields
Royal Observer Corps
Women's Auxiliary Air Force
Battle of Britain
Battle of the Beams
Radar (Chain Home)
German V weapons
Air Raid Precautions in the United Kingdom
RAF strategic bombing offensive
United States Army Air Forces
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